March 14, 2012

Late archaic humans from Longlin and Maludong

This is an extremely important find, as it shows the late persistene of archaic humans in East Asia down to the edge of the Holocene. Archaic humans of the same apparent age have recently been published in Nigeria and there are many finds with a mixture of archaic and modern qualities in Africa, such as the ones from Dar-es-Soltane and Temara mentioned by the authors for North Africa.

The authors propose two different scenaria: one that the archaic specimen from Longlin is derived from a morphologically variable African population; the other that it represents an indigenous archaic remnant.

From the paper:

One widely discussed candidate for the oldest modern human in East Asia is the skeleton from Liujiang, southern China [2]. Yet, the geological age of this individual has “been an everlasting dispute since the discovery of the fossils in 1958” as “there is no documentation on the exact stratigraphic position of the human remains” [4, p. 62]. As a result, its estimated age lies within the broad range of >153-30 ka [2], [4]. The age of the Upper Cave (Zhoukoudian) remains is similarly problematic and has been a major source of uncertainty since their discovery in the 1930s, with estimates ranging from ~33-10 ka [2], [4]. Furthermore, the Niah Cave child from East Malaysia possesses uncertain provenience [5]. However, a recent field and lab program aiming to assess the stratigraphy and dating of the deposits at the site has proposed an age of ~45-39 ka for this cranium [5].

The evidence is slowly mounting for the place of origin of fully modern H. sapiens, as region after region strikes out by having archaic humans present when they are not supposed to be there. Both Sub-Saharan Africa and East Asia have struck out, and Europe had already struck out because of its documented Neandertal population. Australasia is not a valid option due to the lack of precursors, and the Americas because of the their late settlement.

That leaves two options: northernmost Africa (what is now desert) and Arabia/the Gulf Oasis/Indian subcontinent. I'd say that things are looking good for my two deserts theory.

And so it begins. For years, evolutionary biologists have predicted that new human species would start popping up in Asia as we begin to look closely at fossilised bones found there. A new analysis of bones from south-west China suggests there's truth to the forecast.

The distinctive skull (pictured, right) was unearthed in 1979 in Longlin cave, Guangxi Province, but has only now been fully analysed. It has thick bones, prominent brow ridges, a short flat face and lacks a typically human chin. "In short, it is anatomically unique among all members of the human evolutionary tree," says Darren Curnoe at the University of New South Wales in Sydney, Australia.

...

Exactly where the Red Deer Cave people belong in our family tree is unclear. Curnoe says they could be related to some of the earliest members of our species (Homo sapiens), which evolved in Africa around 200,000 years ago and then spread across Asia to reach China. He prefers the idea that they represent a new evolutionary line that evolved in East Asia in parallel with our species, just as Neanderthals did – primarily because they look very different to early African members of our species.

...

Curnoe says an initial attempt to extract good DNA from the fossils failed. "We are doing more work now involving three of the world's major ancient DNA laboratories," he says. "We'll just have to wait and see if we're successful."

PLoS ONE 7(3): e31918. doi:10.1371/journal.pone.0031918

Human Remains from the Pleistocene-Holocene Transition of Southwest China Suggest a Complex Evolutionary History for East Asians

Darren Curnoe et al.

AbstractBackground

Later Pleistocene human evolution in East Asia remains poorly understood owing to a scarcity of well described, reliably classified and accurately dated fossils. Southwest China has been identified from genetic research as a hotspot of human diversity, containing ancient mtDNA and Y-DNA lineages, and has yielded a number of human remains thought to derive from Pleistocene deposits. We have prepared, reconstructed, described and dated a new partial skull from a consolidated sediment block collected in 1979 from the site of Longlin Cave (Guangxi Province). We also undertook new excavations at Maludong (Yunnan Province) to clarify the stratigraphy and dating of a large sample of mostly undescribed human remains from the site.

Methodology/Principal Findings

We undertook a detailed comparison of cranial, including a virtual endocast for the Maludong calotte, mandibular and dental remains from these two localities. Both samples probably derive from the same population, exhibiting an unusual mixture of modern human traits, characters probably plesiomorphic for later Homo, and some unusual features. We dated charcoal with AMS radiocarbon dating and speleothem with the Uranium-series technique and the results show both samples to be from the Pleistocene-Holocene transition: ~14.3-11.5 ka.

Conclusions/Significance

Our analysis suggests two plausible explanations for the morphology sampled at Longlin Cave and Maludong. First, it may represent a late-surviving archaic population, perhaps paralleling the situation seen in North Africa as indicated by remains from Dar-es-Soltane and Temara, and maybe also in southern China at Zhirendong. Alternatively, East Asia may have been colonised during multiple waves during the Pleistocene, with the Longlin-Maludong morphology possibly reflecting deep population substructure in Africa prior to modern humans dispersing into Eurasia.

23 comments:

The evidence is slowly mounting for the place of origin of fully modern H. sapiens, as region after region strikes out by having archaic humans present when they are not supposed to be there. Both Sub-Saharan Africa and East Asia have struck out, and Europe had already struck out because of its documented Neandertal population. Australasia is not a valid option due to the lack of precursors, and the Americas because of the their late settlement.

That leaves two options: northernmost Africa (what is now desert) and Arabia/the Gulf Oasis/Indian subcontinent. I'd say that things are looking good for my two deserts theory.

So let me get this straight, all of Sub-Saharan Africa is no longer an option because of archaic humans in Nigeria?

I don't see how it is parsimonious for Sub-Saharan Africa to be the origin of fully modern Homo sapiens (which would give it the maximum time to assimilate pre-existing archaic hominins, near 180,000 years from Omo to Iwo Eleru), and somehow all these archaics persist there for so long.

Which South Africans are you referring to? If you mean the KRM findings, they date back to the early human expansion, and are not far off from modern variation anyway. They were probably mixed, which explains why modern African hunter-gatherer populations (Khoisan and Pygmies) carry signs of some minor archaic admixture.

I don't know why archaics persisted in Nigeria and the Congo, perhaps early modern humans were not well adapted to that environment? We know modern humans had an early presence in East Africa, regardless of whether they originated there or not.

How is your hypothesis any more parsimonious? Nigeria and Ethiopia are just south of the Sahara. Even the Skhul/Qafzeh humans had some archaic traits, and apparently they didn't make it much further.

It seems to me like early modern humans weren't particularly successful anywhere, prior to the Upper Paleolithic Revolution. That's when they expanded all over Africa and Eurasia, displacing the older inhabitants. Let's not forget that our species is some hundreds of thousands of years old, whereas much of Eurasia was colonized during a much shorter time period.

"Unaligned with typical H. sapiens on supraorbital conformation are the very recent specimens from Fish Hoek and Boskop (Schwartz and Tattersall, 2003) (Fig. 11). The latest estimate of 6891 ± 37 BP for Fish Hoek (Stynder et al., 2009) makes this atypicality all the more intriguing."

As for Klasies River, it is true that they are early, but so are the Mt. Carmel hominins from the Levant, which include what are apparently full blown modern Homo sapiens as well as more archaic individuals. In any case, that is hardly consistent with an African origin. We simply haven't found the hypothesized population that led to Out of Africa on the fossil record.

How is your hypothesis any more parsimonious? Nigeria and Ethiopia are just south of the Sahara. Even the Skhul/Qafzeh humans had some archaic traits, and apparently they didn't make it much further.

The point is that ~15,000 years ago you don't find archaic humans in the Levant, whereas you do find them in Africa. If fully modern H. sapiens originated in Africa, why couldn't it replace archaic Africans in a very long period of time, but apparently replaced archaic Levantines and Neandertals almost immediately?

This is even more troublesome because the Out-of-Africans experienced a whole host of new environments, for which they were not well adapted, but apparently they replaced everyone very quickly, and they couldn't replace archaic Africans in ~200ka?

It seems to me like early modern humans weren't particularly successful anywhere, prior to the Upper Paleolithic Revolution. That's when they expanded all over Africa and Eurasia, displacing the older inhabitants.

Indeed, that is what I refer to when I speak of "fully modern Homo sapiens", in both appearance and behavior. Not sure if you've read my previous posts, but my idea is basically:

Suppose modern humans originated in South Africa as some have speculated.

1. There is no population in South Africa of modern humans in a conventional Out-of-Africa time frame, or any archaeological evidence for Out-of-South Africa; it's all based on evidence of "modern behavior" in sites like Blombos, but there is no reason to think it was made by modern humans anymore than similar "modern behavior" by Neandertals was done by modern humans

2. Said population would have expanded by 10-15 thousand years ago all the way to South America, but apparently would have yet to replace archaic hominins in Nigeria and Central Africa.

Africa is a vast continent, with enormous differences in climate and terrain, diseases. Pygmies and Bushmen live alonside Bantu even now. Why would it be strange that bands of archaic humans would survive in some areas?

We know that anatomically modern humans were in East Africa about 200 kya. There's no evidence of a recent presence of archaic humans in this region. It's also likely that modern humans were in South Africa 100-200 kya.

Moreover, Hofmeyr is quite close to Eurasian UP modern humans, and also considerably older than Iwo Eleru.

Why would you question the origin of mankind in Africa based on the archaic finds? Modern humans had an early presence in Africa, and archaics were still able to persist in Nigeria until recently. Why? Most likely, modern humans didn't have as much of an advantage in parts of Africa as they did in other parts of the world.

I don't see how you could explain it otherwise. Regardless of whether anatomically modern humans originated in Africa or not (which you agree they did anyway?), they were evidently still there. I fail to understand how an origin elsewhere would make a difference. The early humans that migrated into Africa would still have "failed" at displacing the archaics.

We know that anatomically modern humans were in East Africa about 200 kya. There's no evidence of a recent presence of archaic humans in this region. It's also likely that modern humans were in South Africa 100-200 kya.

Not sure what you mean. Omo I is quite robust AMH, but Omo II has archaic features. Herto, which postdates it by 50ka is more archaic. I don't really see how you can exclude the presence of archaic humans in East Africa.

Why would you question the origin of mankind in Africa based on the archaic finds? Modern humans had an early presence in Africa, and archaics were still able to persist in Nigeria until recently. Why? Most likely, modern humans didn't have as much of an advantage in parts of Africa as they did in other parts of the world.

That's an ad hoc explanation. What's so special about the African environment that made them not have an advantage? I mean, they adapted quite well from Siberia to Australia and all over the Americas, spanning every possible ecological zone.

I don't see how you could explain it otherwise. Regardless of whether anatomically modern humans originated in Africa or not (which you agree they did anyway?), they were evidently still there. I fail to understand how an origin elsewhere would make a difference. The early humans that migrated into Africa would still have "failed" at displacing the archaics.

It's quite different if fully modern humans enter Africa c. 35ka and haven't finished replacing the archaics 20ka later, and quite different than them being in Africa since 200ka and haven't finished replacing the archaics 180ka later.

Not sure what you mean. Omo I is quite robust AMH, but Omo II has archaic features. Herto, which postdates it by 50ka is more archaic. I don't really see how you can exclude the presence of archaic humans in East Africa.

This doesn't go against what I said, which was that there were modern humans in East Africa 200 kya, and that there's no evidence of a recent archaic presence. Herto does not qualify as recent.

I didn't exclude the presence of archaics anywhere. But we don't find any recent archaics in East Africa, despite favorable climate for preserving fossils. In Eurasia, however (and admittedly other parts of Africa), we found evidence of all sorts of archaic groups well into the Upper Paleolithic. That's an ad hoc explanation. What's so special about the African environment that made them not have an advantage? I mean, they adapted quite well from Siberia to Australia and all over the Americas, spanning every possible ecological zone.

How would you explain it, then?It's quite different if fully modern humans enter Africa c. 35ka and haven't finished replacing the archaics 20ka later, and quite different than them being in Africa since 200ka and haven't finished replacing the archaics 180ka later.

Do you or do you not deny the presence of anatomically modern humans in Africa 200 kya?

This doesn't go against what I said, which was that there were modern humans in East Africa 200 kya, and that there's no evidence of a recent archaic presence. Herto does not qualify as recent.

What evidence is there of a recent modern presence? I mean, we always read in genetics papers how modern humans left East Africa 60 thousand years ago and took the coastal route or whatever, but where are the actual modern human specimens from East Africa at 60 thousand years?

I am not going to make a 140,000 mental leap and just assume they were there.

How would you explain it, then?

Late arrival of fully modern Homo sapiens. So, you hit two birds with one stone: the archaics in Africa can now be claimed to be better adapted to the environment than the incoming moderns, and there is less time for replacement, allowing the archaics to persist down to the Holocene.

Do you or do you not deny the presence of anatomically modern humans in Africa 200 kya?

Yes, there is evidence of incipient anatomical modernity in 1-2 skuls from one location in East Africa at that time, but no evidence for a population, or for a continuation of that population, or for an exodus of that population, or for any major technological/behavioral advantage over that population 200ka over their more archaic-looking relatives in Africa and elsewhere.

So you propose a Saharan origin for modern humans, whose descendents would die out in Africa before migrating into Arabia, becoming isolated, and finally spreading to populate the world. That would require a pretty massive mental leap.

About the continuation and exodus of a h. sapiens population rooted in Africa, other than the fossils and archaeological data, let us not forget about genetics. Modern L(xM,N) sequences show the continuous evolution of L in Africa, culminating in L3 and the OoA migration.

So you propose a Saharan origin for modern humans, whose descendents would die out in Africa before migrating into Arabia, becoming isolated, and finally spreading to populate the world. That would require a pretty massive mental leap.

I didn't say they died out in Africa. But there's no evidence that they had any sort of advantage over other humans until the UP revolution. It is at that time when the replacement of archaic forms around the world began, a process which lasted longer in Africa and East Asia, because it did not originate in those regions.

About the continuation and exodus of a h. sapiens population rooted in Africa, other than the fossils and archaeological data, let us not forget about genetics. Modern L(xM,N) sequences show the continuous evolution of L in Africa, culminating in L3 and the OoA migration.

As I said elsewhere, I don't see the need to associate any particular morphology with the deepest clades of the mtDNA phylogeny.

As for L3, it probably originated in Eurasia and expanded from there to Africa and the rest of the world after the desertification of Arabia c. 70ka. I won't repeat the arguments for why I hold that position.

Other than political reasons, I don't understand why the authors, as one possibility, propose indigenous origins. Almost all of the measurements and comparisons presented point to a close relationship with AMHs - closest to Cro Magnon and the epipaleolithic, but CM-looking Combe Capelle, in fact.

Admixture? Sure, some of the measurements are either very small, strange, or archaic tending to erectus (as would be expected) - but there is no way these people would have evolved from the archaic erectus present in East Asia, nor from Heidelbergensis-like people. That would mean parallel evolution on a massive scale that is not seen anywhere else in the world.

The National Geographic article mentions stone tools being found along with the bones. How sophisticated was their tool kit and how does it compare to surrounding peoples?The location is very close to Northern Vietnam and Laos, I wonder how well explored that part of South East Asia is.The National Geographic article also mentioned that there are currently three of the top labs in the world working on extracting DNA from the bones.

I dont see why the presence of archaics excludes the possibility of Homo sapiens also being present. Different types of similar primates live alongside each other in fairly close proximity in many locations. Why should hominids be different?

It is clear there was overlap of territory with H neanderthalensis, H erectus and/or the Denisovans (whoever they were).

The roots of Homo sapiens most probably lie in Africa from the genetic evidence as haplogroups near the root are mostly only African. Africans (except NA) don't have the consistent Neanderthal-related admixture common to the rest of us, which fits with leaving them behind in Africa before encountering the Neanderthal-like folk. And your own tree analysis provides the explanation for North Africa.

We are a social creature, not all selective advantages are genetic. I think if you mind-wiped a bunch of adult humans and dumped them in a jungle they would not do well. Scrawny, slow and defenceless. We are not just our genes, we are our culture and learned behaviours. The evidence is that we nearly became extinct several times. We weren't all THAT wonderful.

I didn't say they died out in Africa. But there's no evidence that they had any sort of advantage over other humans until the UP revolution. It is at that time when the replacement of archaic forms around the world began, a process which lasted longer in Africa and East Asia, because it did not originate in those regions.

You said an African origin of "fully" modern homo sapiens was unlikely because they had failed to displace archaics. It seems like your definition of "fully modern humans" is different from the first AMH (because the latter didn't conquer the world?). If that's what you really meant, you should have said so from the start.

I don't see how a more recently evolved modernity would disprove an African origin for humans. If you believe early AMH were not fully modern humans, then that would explain why they didn't displace archaics, and then there's no reason for the more behaviorally modern humans to have originated elsewhere. There's not much of a difference between suggesting that they arose 70 kya in East Africa before the OoA migration, and that they back-migrated very early on (visible in the rich variation of African L3 lineages deriving from the root).As I said elsewhere, I don't see the need to associate any particular morphology with the deepest clades of the mtDNA phylogeny.

This isn't just about L3 (which is most likely African), but also L3'4 and other lineages showing the continuous survival of that population until today.

I concur with Dienekes that the out-of-Africa theory is hampered by 1) the lack of archaeological evidence for the founding migrations; 2) lack of definitive signs of modern human behavior in the Mid-Pleistocene archaeological record in Africa; 3) the vast (180,000) disparity between the dates of extinction of archaic populations and the emergence of modern humans; 4) the mixed bag of archaic and modern features among "anatomically modern humans"; 5) the phylogenetic position of Y-DNA E haplogroup as a subset the of extra-African DECF clade.

It's also noteworthy that Africa was least affected by Pleistocene megafauna extinctions, which again suggests, at least under the anthropogenic theory of extinctions, that modern humans didn't get to Africa until later and in smaller numbers. Otherwise megafauna would have been as affected as it was in Australia but only at an earlier date.

All these themes are further discussed in my new blog at www.anthropogenesis.kinshipstudies.org.

"It's also noteworthy that Africa was least affected by Pleistocene megafauna extinctions, which again suggests, at least under the anthropogenic theory of extinctions, that modern humans didn't get to Africa until later and in smaller numbers. Otherwise megafauna would have been as affected as it was in Australia but only at an earlier date."

One of the possible explanations for this is quite the contrary, maybe the megafauna persisted in Africa exactly because humans evolved here, so the the local megafauna could evolve with them and became more resistant to human predation.

I don't know much about big game hunting during the Upper Paleolithic, but it is my impression that humans couldn't hunt big animals for most of their history. Neandertals could get in close with spears and ambush them -leading to lots of accidents- but the big game changer was the invention of projectile weapons.

So, I don't think that megafauna had much to worry about for most of their co-existence with humans; it was when the latter got projectile weapons that the megafauna had to face a new and dangerous predator.

"One of the possible explanations for this is quite the contrary, maybe the megafauna persisted in Africa exactly because humans evolved here, so the the local megafauna could evolve with them and became more resistant to human predation."

This doesn't make sense: how did giraffes, for example, become more resistant to hominin, then human hunting? Have they been adapting to firearms, too?

I think the most likely hypothesis to explain the survival of african megafauna is due to the higher disease burden in africa.

Africans population prior to the advent of modern medicine was always relatively sparse, now the the ecological constraints of malaria, sleeping sickness, and other tropical diseases has been ameliorated the african population is growing fast and african mega-fauna are going the way of mega fauna everywhere else.

There does seem phenomenon in ecology of animals moving into new environments having an outsized impact but its not as simple as co-evolution with their prey species. It is the removal of ecological constraints in the form of their predators, parasites and diseases as well.

All this does point to africa as the point of origin for humans to some degree but co-evolution with mega-fauna is probably not a super important part of the puzzle.

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